Motor fuel compositions



MOTOR FUEL COMPOSITIONS Paul E. Oberdorfer, Jr., Claymont, Del., assignor to Sun 9H Company, Philadelphia, Pa., a corporation of New No Drawing. Filed Mar. 6, 1957, Ser, No. 544,221

9 Claims. (Cl. 44-63) This invention relates to improved motor fuel compositions, and more particularly 'to a motor fuel containing' a small amount of a cyclic'carbonate. inner ester, sufiicient to substantially reduce engine deposits;

In the operation of internal *combustion engines, whether of the spark ignition or compression ignition type, carbonaceous deposits teudto form in the combustion chambers. In the case of spark ignition engines the problem is serious, since the deposits tend to cause knock, thus increasing the octane number requirement of the engine, and also the carbonaceous material in the deposits has a tendency to burn at low temperatures to form incandescent particles on the combustion chamber walls which cause surface ignition. In compression ignition engines the problem of knock does not occur, but the de'-' posits are undesirable because-they tend .to clog up the fuel injection nozzle.

It is the. object of the, present invention. "to provide a liquid fuel for internal combustion engines effective to reduce the amount of engine deposits, and which is also effective to raise the ignition temperature of such deposits a's, arelformed to a ,value, high enough to prevent the formation of incandescent particles in the combustion chamber, thereby. eliminating ,knockdue to' surface ignition.

I have found that the foregoing objective may be at- .tained if a small quantity of a cyclic carbonate inner ester having the formula:

in which each R may be hydrogen or a hydrocarbon radical, but at least one R is a hydrocarbon radical, is added to a liquid hydrocarbon fuel. Preferred esters are propylene carbonate:

Higher molecular weight carbonates may also be used, such as amylene carbonate and higher homologues, and aromatic carbonates such as phenylethylene carbonate and its homologues, but since the effectiveness of the ad ditive is apparently due solely to the:

group, they are not preferred, since a greater amount of the' ester must be used to produce the same effect. In general, the ester should preferably be added to the fuel in. an amount of from about 0.02% by weight to about 2.0% by weight, although percentages above and below If the fuel is to be used with this range may be used. a clean engine, percentages in the lower part of this range should be used, while if it is desired to use the fuel in an engine which has already accumulated carbonaceous deposits, percentages in the higher portion of ing examples are given:

" Z of 219 hours in order to buildup a substantial amount 4 (Below O.N. Octane No.=12s

of engine deposits, after whicha fuel admixed with 1% propylene carbonate was used. ,The engine was connected to a dynamorneter under a load such that it would takell seconds at'full throttle to'a'ccelerate from "idle 1 to 2500 rpm. The fuels used were rated 'according to' their, performance number, which isrelated to octane" number according to the following equations: "f

1 Performance N o;

('OVer IOO'QNJ'Octane No. i l erformance No.l00

Performance number was used because it is more sensitive than octane number at octanes in the neighborhood of 100. At intervals tests were made to determine the performance number requirement of the engine, that is, the lowest performance number fuel which could be used to permit acceleration under the foregoing conditions without knocking. Results of these tests are set out in the following table.

Table I Performance number Hours on test: requirement 0 92 200 107 As may be seen from the foregoing, 1% propylene carbonate added to the fuel reduced the performance number requirement from 107 to 98.3 within 6 hours, and within 31 hours the requirement had been reduced to the same value as that of a clean engine.

EXAMPLE II In this test the Cadillac engine, freshly cleaned, was run for 200 hours on a fuel containing 0.5% of butylene carbonate. A check run of 200 hours was also made using a fuel without butylene carbonate. At the end of the test the engine was taken apart and the deposits were removed, weighed, and examined for their physical properties. It was found that when the fuel contained butylene carbonate the deposits weighed 25 grams, as

Patented June 7, 1960,

compared to 65 grams when the fuel contained no carbonate, and the ignition temperature of the deposits was over 460 C., the upper limit of the testing apparatus, as compared to an ignition temperature of only 164 C. for the deposits formed when the fuel contained no carbonate.

While the foregoing examples were limited to the use of my new fuel compositions in spark ignition engines, the cyclic carbonates are equally effective when added to diesel fuel oils to reduce engine deposits, and the in vention should be construed as covering diesel fuel oils Containing the carbonates as well as gasolines.

In the appended claims, when the expression consisting essentially ofis used, it should not be construed as limiting the claimed fuel to a composition containing solely the ingredients named in the claim, but should be construed as covering fuels containing other additives customarily found in commercial fuels, such as gum inhibitors, anti-rust agents, antioxidants and the like, and in addition, in the ease of gasoline, anti-knock agents such as tetraet-hyl lead, and ethylene halide lead scavengers, and in the case of diesel fuel oil, cetane irnprovers.

This application .is a continuation-m-part of my copending application Serial No. 595,055, filed July 2, 1956.

The invention claimed is:

1. A new composition of matter consisting essentially of a normally liquid hydrocarbon internal combustion engine fuel together with a cyclic carbonate inner ester having the formula: I I

in which R, is. selected from the group consisting of hydrogen and hydrocarbon radicals, and R is a hydrocarbon radical, saidester being present in the composition in anamount, small but suflicientto substantially lessen engine deposit accumulation.

- 2. The composition of claim 1 in which the ester is propylene carbonate.

3. The composition of claim 1 in which the ester is butylene carbonate.

4. A new composition of matter consisting essentially of a hydrocarbon fraction boiling within the gasoline boiling range, together with a cyclic carbonate inner ester having the formula:

. REC-O in which R 'is selected from the group consisting of hydrogen and hydrocarbon radicals, and R is a hydrocarbon radical, said ester being present in an amount small but suflicient to substantially lessen engine {deposit accumulation.

5. "The COmpOSi'tiO'Ii "Of claim 4"ii1 which the ester is propylene carbonate.

6. The composition of claim 4 in which the ester is butylene carbonate.

7. A new composition of matter consisting essentially of a hydrocarbon fraction boiling in thediesel fuel oil range, together with a cyclic carbonate inner ester having the formula:

RRC-O o=o BRC O in which 'R is selected from the group consisting of hydrogen and hydrocarbon radicals, and R is a hydro carbon radical, said ester being present in an amount small but sufiicient to'subs'tantially lessen engine deposit accumulation. v

8. The composition according to claim 7 in which the ester is propylene carbonate.

9. The composition according to claim 7 in which the ester is butylene carbonate.

References Cited in thefile of this patent UNITED STATES PATENTS 

1. A NEW COMPOSITION OF MATTER CONSISTING ESSENTIALLY OF A NORMALLY LIQUID HYDROCARBON INTERNAL COMBUSTION ENGINE FUEL TOGETHER WITH A CYCLIC CARBONATE INNER ESTER HAVING THE FORMULA: 